In a process of manufacturing a semiconductor device, if the processing of a substrate is not carefully performed, the film previously formed on the substrate may be damaged. For example, when a plasma treatment such as etching or ashing is performed on a porous low dielectric constant film used as an interlayer insulating film in order to embed a wiring, the low dielectric constant film is damaged. Specifically, the porous low dielectric constant film is, for example, a SiOC film containing silicon, carbon, oxygen and hydrogen and having Si—C bonds. On an exposed surface of the SiOC film exposed to plasma, namely on a side wall and a bottom surface of a recess, for example, the Si—C bonds are broken by plasma and C is desorbed from the film. Si having unsaturated bonds generated due to desorption of C is unstable in that state. Thus, Si is bonded to, for example, moisture in the atmosphere, to become Si—OH constituting a damaged layer.
For example, a technique has been used in which a PMMA (acrylic resin) is embedded in advance in pores of a porous low dielectric constant film formed on a substrate, a process such as etching or the like is performed on the low dielectric constant film, the substrate is heated, a solvent is supplied, and a microwave is supplied to remove the PMMA. However, in order to remove the PMMA, it is necessary to spend a long period of time of about 20 minutes in a plasma treatment and to heat the substrate to a temperature of 400 degrees C. or higher. Therefore, there is a great concern that element portions already formed in the substrate may be adversely affected.
As another example, there is an example in which, in a process of manufacturing a memory element, a surface (interface) of an electrode film is oxidized to form a damaged layer as an oxide layer when a contact hole is formed by a plasma treatment. In this process, first, an electrode film and a mask (etching mask) film are laminated on a memory element film, for example, a metal oxide film, to form a laminate. Then, the laminate is etched. Subsequently, an insulating film is formed on the substrate. The laminate left by etching is buried in the insulating film. Then, the insulating film on the laminate is etched by the plasma treatment to form the contact hole.
In the plasma treatment, the mask film is over-etched, and a damaged layer (oxide layer) is formed at the interface of the electrode film. Thus, for example, a reduction treatment is performed by hydrogen annealing or the like. However, there is a possibility that the removal of the damaged layer becomes insufficient even if the reduction treatment is performed.
Furthermore, in the concept of thermal decomposition of a resin, it is known that as the resin removal temperature decreases, a heat resistant temperature of the resin also decreases. It is also known that only a PMMA can be thermally unstuffed at 400 degrees C., which is an allowable temperature in a wiring process. However, the thermal stability of the PMMA drops to 250 degrees C. This means that if a temperature of 250 degrees C. or higher is applied to the PMMA during a protection process using the PMMA, a PMMA film deteriorates so that it cannot be used as a protective film.
Therefore, the technique described above is not a technique in which a protective film functions as a protective film even when a thermal process is performed at a temperature exceeding a protective film removal temperature as in the present disclosure.